A Biomimetic Nanoparticle for pDNA Delivery and Expression in Plant Cells in a pH-Dependent Manner

Stimuli-responsive gene delivery vectors based on structuralchangestriggered by environmental conditions have been widely studied inanimals because of their excellent performance in vivo. However, theirinvestigations in plants have lagged behind. Herein, we present asmart gene delivery system based on polyethylenimine (PEI)-modifiedcarbon dots, called amine-functionalized carbon dots (A-CDs), whichare pH-responsive, surface charge-switching, and capable of enhancingnuclear import of genes. Due to the amine groups on the surface ofA-CDs, the DNA-CD complex has a positive surface charge atpH 5.7, which will facilitate crossing the cell wall and cell membrane.The amine groups in the side chains of the complex can lose protonsand promote DNA release in the nucleus in a weakly alkaline environment.Such A-CDs, which mimic the work of nucleosomes, promote an increasedaccessibility of DNA to complete transcription. In the model planttobacco, leaves transfected with DNA-CD complexes of greenfluorescent protein sequence exhibited distinct green fluorescenceunder confocal microscopy. This suggests that this smart vector canbe used to transiently transfect mature intact plants. Taken together,studies targeting the binding behavior of DNA-CD complexesat different pH values can help to develop more effective gene deliveryvector materials.